Estrogen's Effects on the Female Body

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What is estrogen?

Estrogen is a group of hormones that play an important role in the normal sexual and reproductive development in women. They are also called sex hormones. The woman's ovaries produce most estrogen hormones, although the adrenal glands also produce small amounts of the hormones.

In addition to regulating the menstrual cycle, estrogen affects the reproductive tract, the urinary tract, the heart and blood vessels, bones, breasts, skin, hair, mucous membranes, pelvic muscles, and the brain. Secondary sexual characteristics, such as pubic and armpit hair, also begin to grow when estrogen levels rise. Many organ systems, including the musculoskeletal and cardiovascular systems, and the brain are affected by estrogen.

Hormone replacement therapy update

To learn more about women's health, and specifically hormone replacement therapy, the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH) launched the Women's Health Initiative (WHI) in 1991. The hormone trial had two studies: the estrogen-plus-progestin (HRT) study of women with a uterus and the estrogen-alone (ERT) study of women without a uterus. Both studies were concluded early when the research showed that hormone replacement did not help prevent heart disease and it increased risk for some medical problems.

The FDA states that hormone therapy should not be taken to prevent heart disease.

These products are approved therapies for relief from moderate to severe hot flashes and symptoms of vulvar and vaginal atrophy. Although hormone therapy may be effective for the prevention of postmenopausal osteoporosis, it should only be considered for women at significant risk of osteoporosis who cannot take non-estrogen medications. The FDA recommends that hormone therapy be used at the lowest doses for the shortest duration needed to achieve treatment goals. Postmenopausal women who use or are considering using hormone therapy should discuss the possible benefits and risks to them with their health care providers.

The National Heart, Lung, and Blood Institute offers the following suggestions for women who are deciding whether or not to use postmenopausal hormone therapy:

Because the study involved healthy women, only a small number of them had either a negative or positive effect from estrogen plus progestin therapy. The percentages describe what would happen to a whole population—not to an individual woman. In the estrogen plus progestin therapy study the increase risk for breast cancer was eight additional cases for every 10,000 women over one year; there was a 24 percent increase overall.

The most important thing a woman can do in deciding to continue hormone replacement therapy is discuss the current research with her health care provider and health care team.

Women need to be aware that taking a combined progesterone and estrogen regimen or estrogen alone is no longer recommended to prevent heart disease. A woman should discuss other alternatives of protecting the heart with her health care provider.

Women should discuss with their health care providers the value of taking combined progesterone and estrogen replacement therapy or estrogen to prevent osteoporosis. There may be alternative treatments based on a woman's unique health profile.